A laminated glass generally has a structure in which a resin is sandwiched between two inorganic glass sheets, and a number of laminated glasses are used as window members for buildings, automobiles, railway vehicles, and the like. Compared with a general window glass in a single sheet form, the laminated glass is excellent in strength and toughness in a glass surface and has durability against an external force, and hence, destruction and penetration are unlikely to occur. Due to such performances, the laminated glass is useful as a window member that requires security and safety. The laminated glass may exhibit various performances by selecting a material of a resin. Therefore, a novel resin has been studied, and a laminated glass, which is excellent in various additional performances, such as acoustic insulation and heat insulation, has been realized.
As described above, the laminated glass are installed on a large number of buildings, automobiles, and the like, and many inventions have been made for further enhancement of the performance and quality thereof. For example, Patent Document 1 discloses a laminated glass, glass fragments of which hardly scatter at the time of breakage, and which is excellent in acoustic insulation. This prior art involves using two kinds of polyvinyl acetal resin films, to thereby prevent the acoustic insulation from being lowered, caused by a coincidence effect. The coincidence effect refers to a phenomenon that, when a sound wave enters the glass, a transverse wave is transmitted on a glass surface due to stiffness and inertia of the glass, and the transverse wave and the incident sound resonate to cause transmission of a sound. Patent Document 2 discloses a laminated glass which is excellent in impact resistance and delamination resistance with respect to incoming flying substances and the like. This prior art involves inserting laminated intermediate films made of two or more kinds of resins having different Young's moduli between glass sheets to achieve tight integration. Patent Document 3 discloses a safety laminated glass, scattering of which is unlikely to occur even when the glass is broken by an external force. This prior art involves mixing an organic peroxide and a silane coupling agent in an ionomer resin in which molecules of ethylene-methacrylic acid copolymers are bonded by metal ions, inserting a thermosetting resin thus obtained between glass sheets, and achieving their integration by heat curing. Patent Document 4 discloses a laminated glass, glass fragments of which do not scatter even when the glass is broken. This prior art involves injecting a polymerizable composition containing polycarbonate, pentaerythritol tetra (3-mercaptopropionate), and a photopolymerization initiator between two glasses, and curing the resins by photopolymerization to form a resin layer.    Patent Document 1: JP 07-206483 A    Patent Document 2: JP 2003-192402 A    Patent Document 3: JP 09-30846 A    Patent Document 4: JP 11-236252 A